The present invention relates generally to the field of sheet pilings, and, more particularly, to an improved sheet piling having a substantially Z-shaped transverse cross section.
A variety of Z-shaped steel sheet pilings are known in the prior art. Z-shaped sheet pilings are typically produced in a number of different sizes, each characterized by its approximate weight in pounds per square foot (xe2x80x9cpsfxe2x80x9d). Typical sizes include the PZ22, PLZ23, PLZ25, PZ27, PZ35, and the PZ40. One of the most widely used sheet piling is the PZ27. Such sheet pilings were widely produced by Bethlehem Steel Corporation and United States Steel Corporation. The PZ22 and PZ27 sections are now produced by Nucor-Yamato.
However, the strength criteria previously used to design the cross section of Z-shaped sheet piling was based on the section modulus of the piling. The cross-sectional design for the Z-shaped sheet piling did not incorporate or take into account transverse stresses; i.e., those stresses oriented perpendicularly to the longitudinal axis of the sheet piling. Consequently, known Z-shaped sheet pilings did not have great resistance to transverse loading.
Hence, it would be useful to provide a Z-shaped sheet piling in which the cross-sections are designed so as to resist transverse stresses.
With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, the present invention provides an improved Z-shaped sheet piling (15) having a first flange (16), a web (19), a second flange (18), a section modulus of at least about 25 in3/ft., a weight of less than about 31 lbs./ft.2, and the second flange having a wale location (68). The improvement comprises the web, first flange and second flange being so dimensioned and configured that the transverse stress at the wale location for each psi of applied load is less than about 1000 pounds per square inch (xe2x80x9cpsixe2x80x9d). The transverse stress at the wale location may be about 878 psi per psi of applied pressure load.
The present invention also provides a Z-shaped sheet piling having a first flange, a web and a second flange, the first flange having a span location (65 or 66). The improvement comprises the web, first flange and second flange being so dimensioned and configured that the transverse stress at the span location for each psi of applied load is less than about 800 psi. The transverse stress at the span location may be about 731 psi per psi of applied load or may be about 786 psi per psi of applied load.
The Z-shaped sheet piling may have a moment of inertia of about 188.66 in.4/ft. The Z-shaped sheet piling may have a section modulus of about 30.97 in3/ft., may have a weight of about 27.56 psf, and may have a cross-sectional area of about 12 in2.
Accordingly, the general object of the present invention is to provide an improved Z-shaped sheet piling which is able to accommodate transverse stresses.
Another object is to provide an improved Z-shape sheet piling which has greater margins of safety when in use.
Another object is to provide an improved Z-shaped sheet piling which takes into account the transverse stresses when in actual use.
Another object is to provide a Z-shaped sheet piling which has a weight of about 27 psf.
Another object is to provide a Z-shaped sheet piling which is stronger at those points where it is necessary to resist transverse stresses.
Another object is to provide a Z-shaped sheet piling which reduces the deleterious stress.